一、bright()
语法：str.ljust(width,[fillchar])
Parameter description:
width – specifies the length of the string.
fillchar – fill character, default is space.
Return value: Returns a new string with the original string left-aligned and padded with spaces to a length of width. If the specified length is less than the length of the original string, the original string is returned.
str = "this is string example....wow!!!"
print(str.ljust(50, '0'))
# this is string example....wow!!!00000000
Two, rjust()
语法：str.rjust(width,[fillchar])
Parameter description:
width – specifies the length of the string.
fillchar – fill character, default is space.
Return Value: Returns a new string with the original string right-aligned and padded with spaces to a length of width. If the specified length is less than the length of the original string, the original string is returned.
str = "this is string example....wow!!!"
print(str.rjust(40, '0'))
# 00000000this is string example....wow!!!
3. zfill(width)
语法：str.zfill(width)
width – Specifies the length of the string. The original string is right-aligned and filled with 0 in front.
Returns a string with a length of width, the original string is right-aligned, and the front is filled with 0
str = "this is string example....wow!!!"
print(str.zfill(40))
# 00000000this is string example....wow!!!
print(str.zfill(50))
# 000000000000000000this is string example....wow!!!
Four, string.center(width)
语法：str.center(width, [fillchar])
width – The total width of the string. fillchar – fill character.
Returns a new string with the original string centered and padded with spaces to length width
（如果不指定填充字符，默认填充符为空格）
str = 'runoob'
print(str.center(20, '*'))
# '*******runoob*******'
print(str.center(20))
# ' runoob '